docs: def _sections_to_raw_data(sections):
      '''convert list of sections into the `raw_data` format used in neurom
  
      This finds the soma, and attaches the neurites
      '''
      soma = None
      neurites = []
      for section in sections:
          neurite = _extract_section(section)
          if neurite is None:
              continue
          elif neurite[0][COLS.TYPE] == POINT_TYPE.SOMA:
              assert soma is None, 'Multiple somas defined in file'
              soma = neurite
          else:
              neurites.append(neurite)
      assert soma is not None, 'Missing CellBody element (ie. soma)'
  
      total_length = len(soma) + sum(len(neurite) for neurite in neurites)
      ret = np.zeros((total_length, 7,), dtype=np.float64)
      pos = len(soma)
      ret[0:pos, :] = soma
  
      for neurite in neurites:
          end = pos + len(neurite)
          ret[pos:end, :] = neurite
          ret[pos:end, COLS.P] += pos
          ret[pos:end, COLS.ID] += pos
          # TODO: attach the neurite at the closest point on the soma
          ret[pos, COLS.P] = len(soma) - 1
          pos = end
  
      return ret